I was playing Terraria on my mobile device, when I came across an item called the Valentine Ring. I purchased it, thinking it did something cool (the tooltip wasn't being displayed for some reason), but I can't figure out what it does. Can somebody explain it to me?
According to the wiki there is no item called the Valentine Heart. But if it were it'd be added in the Valentine update.
Maybe you mean the Broken Heart Crystal?. It summons a cupid pet, which is pretty much the same as the Wisp in a Bottle, i.e., a moveable light source.
It's probably not a Heart Arrow (which stuns enemies) or the Valentine Ring (which gives you extra jump height and 50% health regen if it were given to you by another person). Those two items are the others added during the Valentine Update.
If it is called a Valentine Heart I'd love a screenshot to find out more =p
Dropping it on the ground and picking it up again should activate The powers mentioned by Kevin van der velden, according to the wiki.
To drop an item in pocket edition, drag the item to the ground from your hotbar while your inventory is closed.
You could just put it into a chest and then take it out, r you could drop it then pick it up. It gives a 50% increased jump height and an increased health regeneration. The helpful tooltip will show after you activate it by doing what I mentioned above. This website might help: http://terraria.gamepedia.com/Valentine_Ring